Time-sharing compression system

ABSTRACT

A compression system employing a compressor having an inlet and an outlet, at least one intermediate pressure accumulator and valving to cyclically communicate first the compressor outlet with the accumulator and then the compressor inlet with the accumulator whereby a higher system compression ratio is obtained than that produced across the compressor itself.

Unlted States Patent 11 1 1111 3,844,689 Weatherston Oct. 29, 1974 TIME-SHARING COMPRESSION SYSTEM FOREIGN PATENTS OR APPLICATIONS [75] Inventor: {Erfier C. Y'eagliesrs on, 1,099,021 3 1955 France 418/l8l 1 lamsvi e,

[73] Assignee: Calspan Corporation, Buffalo, NY. Primary Examiner-william L. Freeh Assistant Examiner-Richard E. Gluck [22] Flled' 1973 Attorney, Agent, or FirmAllen J. Jaffe [21] Appl. No.: 329,284

[57] ABSTRACT 52] US. Cl. 417/572, 417/244 A compression System employing a compressor having [51] Int. Cl. F04b 21/00, F04b 39/00 an inlet and an outlet at least one intermediate [58] Field of Search 417/540, 252, 244, 250, l l n p 417/251 442 572 53, 60/371 sure accumu ator an va ving to cyc ica y communi- 4133/1 1 cate first the compressor outlet with the accumulator and then the compressor inlet with the accumulator whereby a higher system compression ratio is obtained [56] g g ifzfi gs gii s than that produced across the compressor itself. 1,759,6l7 5/1930 Hoerbizer 417 250 20 Claims, 1 Drawing Figure ACTUATOR COMPRESSOR PATENIEMm 29 I97? ACTUATOR COMPRESSOR 1 TIME-SHARING COMPRESSION SYSTEM BACKGROUND OF THE INVENTION The present invention relates to an apparatus for compressing gaseous fluids which, although incorporating a single compressor, is capable of efficiently achieving compressionrations greatlyin excess of those efficiently obtainable heretofore with but a single compressor.

By way of example and not limitationthe apparatus according to the presentv invention finds particular application with rotary compressors of the Roots-type.

At low flow capacities, below 100 cubic feet per minute for example, thereciprocating compressor is small, practical and efficient. At large capacities, above 2000 cubic feet per minute for example, the centrifugal compressor is effective. However, at the range of capacities between I and 2000 cubic feet per minute rather large and costly recipricating compressors or rather inefficient small centrifugal compressors have been employed as comprises between cost and performance. Additionally, the sliding vane-type compressorand the screw compressor have been used in the above mentioned 100 to 2000 capacity range.'These compressors require large amounts of oil 'forlubrication and sealing, which'oil must be separated to prevent contamination of the air or other gas being handled. Such separation is never complete and for many applications oil cannot be tolerated in the-"gas b'eing'handled.

In general, there aremany applications which require overall compression rations whichexceed the allowable compression ratio of'a'single compressor. In such cases it has been'necessary to employ multiple stages of compression through multiple compressors. This requires a duplication of equipment which is costly and cumbersome;

SUMMAR OF THE INVENTION The present invention provides a compression system which overcomes the above mentioned difficulties of the prior art.

The present invention provides a system which enables a single compressor to satisfy the needs of a compression requirement that ordinarily would require the use of two or more compressors operating'in a series arrangement. This is accomplished by time-sharing the use of a single compressor so'that it is used first to compress the gas from the initial pressure level to an intermediate pressure level and then, at a later time, the same compressor reingests the gas at the intermediate pressure and compresses it to the final dischargepressure. An accumulator or pressure storage vessel is provided to store the gasfor a short period of time at the intermediate pressure level and valving means is provided to permit the compressor inlet to communicate first with gas at the initial pressure and then with the accumulator at the intermediate pressure and to permit the compressor outlet to communicate first with the intermediate pressure accumulator and then with the system outlet at final discharge pressure which may include asecond accumulator at the final discharge pressure. The actuation of such valving means may be controlled by the pressure-in theintermediate accumulator or by a timer.

Basically then, the present invention provides a compression system comprising a compressor having an inlet and an outlet,;at least .one intermediate pressure storage means and valving means for cyclically placing the storage means first in communication with the compressor outlet and then in communication with the compressor inlet, whereby the compressor first delivers gas at the intermediate pressure and then delivers gas at a higher final discharge pressure.

BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of the present invention reference should now be had to thefollowing detailed description thereof taken in conjunction with the accompanying drawing wherein the only FIGURE represents a schematic flow diagram of the compression apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing a compressor, which may be preferably of the Roots-type or any other type, is depicted schematically at 10 and has an inlet passage 12 and an outlet passage 14. Suitable valving means depicted illustratively and generally as a multi-way spool type valve 16 is provided for cyclically providing communication between the compressor 10, a source of initial low pressure. 18, an intermediate pressure reservoir or accumulator 20 and a high pressure final discharge line 22 as will become apparent hereinbelow.

Valve 16 comprises a housing 24 in which is located a reciprocating spool 25 having sealing lands 26,28 and 30. Housing 24 contains port 32 in fluid communication with a low pressure supply passage 18, port 34 in fluid communication with compressor inlet 12, port 36 in fluid communication via line 38-with intermediate pressure accumulator 20, port 40 in fluid communication with compressor outlet 14, and port .42 in fluid communication with high pressure discharge line 22. Discharge line 22 may contain a high pressure accumulator 44 for supplying gas to a point of utilization via line 46.

In the position of valve spool 25 illustrated port 32 communicates with port 34 permitting low pressure gas from line 18, or the atmosphere in the case of air,'to be supplied to compressor inlet 12. The low pressure gas is compressed in the compressor to an intermediate pressure and is delivered via compressor outlet 14 through ports 40 and 36 to intermediate accumulator 20 via line 38. In this position port 42 is blocked by land 30 from communication with port 40.

When the pressure in accumulator 20 reaches its desired intermediate pressure level spool valve 25' is switched to its second position by actuator 48 whereat port 34 communicates with port 36 and port 40 com municates with port 42; port 32 being blocked from communication with port 34 by land 26. In this second position gas at the intermediate pressure from accumulator 20 is delivered to the compressor inlet '12 from line 38 and ports 36 and 34. The gas undergoes additional compression from the intermediate pressure to the final high discharge pressure and is delivered from compressor outlet 14 to high pressure discharge line 22 via ports 40 and 42. After a suitable time spool 25 is moved to its first position and the cycle is repeated;

Valve spool 25 should be switched fast enough so that the pressure level in intermediate accumulator 20 is kept at the desired average intermediate pressure level plus or minus 10 or 20 percent, but slow .enough so that many cycles of compressor action are completed in each valve position. This insures that the volume of gas in lines 12 and 14 (which undergoes a wasteful pressure change when switched) is small compared to the throughput volume of the compressor. Lines 12 and 14 should be kept short which dictates that compressor be as close as possible to valve 16. For most applications the valve should remain in each of its two positions for from 0.1 to seconds. Actuator 48 may be any well known type of valve actuator and it may be responsive to a timer or, alternatively, to the pressure level within accumulator 20. The actual structure for controlling actuator 48 is well known to those skilled in the art and is not further described herein.

It can thus be seen with the apparatus according to the present invention the pressure ratio between discharge line 22 and inlet line 18 is higher than it would be across the compressor 10 functioning by itself.

Although a preferred embodiment of the present invention has been described changes will occur to those skilled in the art. For example two or more accumulators at two or more intermediate pressure levels could be employed to reduce the required compression ratio across the compressor itself to thereby increase the efficiency of the overall compression process or for the same efficiency a higher overall system compression ratio could be obtained. It is therefore intended that the invention is to be limited only by the scope of the appended claims.

What is claimed is: 1. in a time-sharing compression system, the combination comprising:

a. a compressor having an inlet and an outlet, and a source of low pressure fluid b. accumulator means including at least one pressure reservoir for storing gas at at least one intermediate pressure, above that of said low pressure fluid and c. first valving means for cyclically placing said reservoir first in communication only with said compressor outlet and then in communication only with said compressor inlet whereby said compressor first delivers gas at one or more intermediate pressures above said low pressure fluid and then delivers gas to a discharge passage at a final higher pressure.

2. The system according to claim 1, further comprisd. second valving means for placing said discharge passage in communication with said compressor outlet when said reservoir is in communication with said compressor inlet.

3. The system according to claim 2, wherein;

e. said first and second valving means comprising a multi-way type valve having two operative positions.

4. The system according to claim 3, wherein;

f. said valve remains in each of its operative positions for from 0.1 to 20 seconds.

5. The system according to claim 1, wherein;

d. said reservoir is in communication with said compressor inlet for from 0.1 to 20 seconds.

6. The system according to claim 5, further comprisf. valving means for placing said discharge passage in communication with said compressor outlet when said reservoir is in communication with said compressor inlet. 7. In a time-sharing compression system, the combination comprising; 5 a. a compressor having an inlet and an outlet, and a source of low pressure fluid b. accumulator means including at least one pressure reservoir for storing gas at at least one intermediate pressure above that of said low pressure fluid,

c. a final discharge gas passage, and

d. a multi-way type valve having two operative positions for cyclically placing said reservoir first in communication with said compressor outlet and then in communication with said compressor inlet and for placing said final discharge gas passage in communication with said compressor outlet when said reservoir is in communication with said compressor inlet.

8. In a time-sharing compression system, the combination comprising;

a. a compressor having an inlet and an outlet, and a source of low pressure fluid b, accumulator means including at least one pressure reservoir for storing gas at at least one intermediate pressure level between that of said low pressure fluid and a final higher discharge pressure level, and

c. valving means having two operative positions, in

the first of which communication is established between said compressor outlet and said reservoir and communication is blocked between said reservoir and said compressor inlet, in the second operative position of which communication is established between said compressor inlet and said reservoir and communication is blocked between said reservoir and said compressor outlet whereby said compressor outlet first contains gas at one or more intermediate pressure levels and then delivers gas to a discharge passage at a final higher discharge pressure level.

9. The system according to claim 8, wherein said valving means remains in each of its operative positions for a predetermined period of time.

10. The system according to claim 9 wherein said predetermined period of time is from 0.1 to 20 seconds.

11. The system according to claim 9, wherein said predetermined period of time is sufiicient for said compressor to undergo many cycles of compressor action.

12. The system according to claim 8, wherein the actuation of said valve means from one of its operative positions to the other is responsive to the pressure level in said accumulator means.

13. The system according to claim 8, wherein the actuation of said valving means from one of its operative positions to the other is responsive to the elapsing of a predetermined period of time.

14. The system according to claim 8, wherein the actuation of said valving means from one of its operative positions to the otheris cyclic and repetitive according to predetermined conditions.

15. The system according to claim 8, wherein said valving means comprises a multi-way type valve.

The system according to claim 8, further comprising:

for a period of time sufficient for said compressor to undergo many cycles of compressor action.

19. The system according to claim 18 wherein said compressor is of the rotary-type.

20. The system according to claim 8, wherein said compressor is of the rotary-type. 

1. In a time-sharing compression system, the combination comprising: a. a compressor having an inlet and an outlet, and a source of low pressure fluid b. accumulator means including at least one pressure reservoir for storing gas at at least one intermediate pressure, above that of said low pressure fluid and c. first valving means for cyclically placing said reservoir first in communication only with said compressor outlet and then in communication only with said compressor inlet whereby said compressor first delivers gas at one or more intermediate pressures above said low pressure fluid and then delivers gas to a discharge passage at a final higher pressure.
 2. The system according to claim 1, further comprising; d. second valving means for placing said discharge passage in communication with said compressor outlet when said reservoir is in communication with said compressor inlet.
 3. The system according to claim 2, wherein; e. said first and second valving means comprising a multi-way type valve having two operative positions.
 4. The system according to claim 3, wherein; f. said valve remains in each of its operative positions for from 0.1 to 20 seconds.
 5. The system according to claim 1, wherein; d. said reservoir is in communication with said compressor inlet for from 0.1 to 20 seconds.
 6. The system according to claim 5, further comprising; f. valving means for placing said discharge passage in communication with said compressor outlet when said reservoir is in communication with said compressor inlet.
 7. In a time-sharing compression system, the combination comprising; a. a compressor having an inlet and an outlet, and a source of low pressure fluid b. accumulator means including at least one pressure reservoir for storing gas at at least one intermediate pressure above that of said low pressure fluid, c. a final discharge gas passage, and d. a multi-way type valve having two operative positions for cyclically placing said reservoir first in communication with said compressor outlet and then in communication with said compressor inlet and for placing said final discharge gas passage in communication with said compressor outlet when said reservoir is in communication with said compressor inlet.
 8. In a time-sharing compression system, the combination comprising; a. a compressor having an inlet and an outlet, and a source of low pressure fluid b. accumulator means including at least one pressure reservoir for storing gas at at least one intermediate pressure level between that of said low pressure fluid and a final higher discharge pressure level, and c. valving means having two operative positions, in the first of which communication is established between said compressor outlet and said reservoir and communication is blocked between said reservoir and said compressor inlet, in the second operative position of which communication is established between said compressor inlet and said reservoir and communication is blocked between said reseRvoir and said compressor outlet whereby said compressor outlet first contains gas at one or more intermediate pressure levels and then delivers gas to a discharge passage at a final higher discharge pressure level.
 9. The system according to claim 8, wherein said valving means remains in each of its operative positions for a predetermined period of time.
 10. The system according to claim 9 wherein said predetermined period of time is from 0.1 to 20 seconds.
 11. The system according to claim 9, wherein said predetermined period of time is sufficient for said compressor to undergo many cycles of compressor action.
 12. The system according to claim 8, wherein the actuation of said valve means from one of its operative positions to the other is responsive to the pressure level in said accumulator means.
 13. The system according to claim 8, wherein the actuation of said valving means from one of its operative positions to the other is responsive to the elapsing of a predetermined period of time.
 14. The system according to claim 8, wherein the actuation of said valving means from one of its operative positions to the other is cyclic and repetitive according to predetermined conditions.
 15. The system according to claim 8, wherein said valving means comprises a multi-way type valve.
 16. The system according to claim 8, further comprising: d. additional valving means for placing said discharge gas passage in communication with said compressor outlet.
 17. The system according to claim 16, wherein said valving means and said additional valving means comprise a multi-way type valve.
 18. The system according to claim 16, wherein said valving means remains in each of its operative positions for a period of time sufficient for said compressor to undergo many cycles of compressor action.
 19. The system according to claim 18 wherein said compressor is of the rotary-type.
 20. The system according to claim 8, wherein said compressor is of the rotary-type. 